At the front of a conventional motor vehicle, there are generally to be found a bumper cross-member, an air inlet grille, and possibly a bottom part which can constitute a spoiler member, protection for the engine, or a bottom bar that acts in the event of a collision with a pedestrian. 
These various portions are made up of separate parts made of various materials which are assembled together on the vehicle, generally by means of screws, at predetermined anchor points. 
These parts are independently designed so that each of them presents the required mechanical properties, depending on its own functions. 
This gives rise to an assembly made up of these three parts which is relatively heavy, since each part on its own is required to perform the function assigned to it. 
Japanese patent application 55 137 760 describes a structure having a cross-member for receiving a bumper. 
Such a support structure does not itself comprise a bumper, with the bumper being constituted by a distinct part fitted thereto. 